// CF_TR5_A
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <stdio.h>
#include <fstream>
#include <cmath>

using namespace std;

int main()
{
    long double x, y;
    ifstream file_in("angle1.txt");
    file_in >> x >> y;
    file_in.close();

    long double ang = 0;
    ang = atan2(y, x);

    ofstream file_out("angle2.txt");
    //file_out << ang;
    fprintf(file_out, "%.10d", ang);
    file_out.close();

    system("pause");
    return 0;
}